General Relativity Quandary

I’m just having a hard time getting my mind around some science concepts today. Maybe it’s my new drugs (methylphenidate, generic Ritalin), but things which I only used to have mild discomfort trying to grasp are now screaming out, help I’m not making sense!

Yea, I know what Einstein said about “common sense” being things which are drilled into your head before eighteen and how if we had spent the first eighteen years of our lives flying about the universe in close to light velocity spacecraft common sense might actually make sense.

Still, anytime something seems paradoxical or contradictory it says to me, either my understanding of the model is incomplete or the model itself is flawed. So I post these things hoping someone who thinks they understand it can explain it to me.

Here is my current general relativity quandary… As I understand general relativity, the underlying principal is that all reference points are equally valid.

The Hafele-Keating experiment put atomic clocks on commercial airlines and compared them to clocks on the ground in the US naval observatory. I first heard of this vaguely and the way I heard it was they flew one clock around the world, they kept the other on the ground, and the one flown around the world and when they landed the time was different, and the way I heard it, the flown clock was slightly slower.

Now actually there are two issues here. There is gravitational time dilation and that one I’m only a little uncomfortable with (but I’m still uncomfortable) and there is kinematic time dilation that I am a lot uncomfortable with.

The reason I am uncomfortable with the kinematic time dilation component is this; if all frames of reference are equally valid, then it is equally valid to say the plane went up and then circled around the earth, as it is to say the plane went up and the earth circled underneath the plane and it came back down. In other words, what moved relative to what?

The moving clocks are moving relative to each other so I don’t see how one can gain and one can lose time relative to one another. It seems terribly arbitrary deciding which clock should go slower than the other because both should appear to go faster relative to the other from the others point of view. But when they’re back together stationary seems to me like that ought to cancel and they should stay the same but of coarse they don’t.

Now the gravitational time dilation, at least I can see what is different in terms of the reference points, one is in a gravitational well, one is to a lesser degree, and time flows at different rates within that well.

But the time dilation one I’m having problems grasping, especially when it matters if it’s east-west or west-east. Yea, I know it’s a different velocity but it’s a relative velocity either way. Why should one frame of reference be favored?